Canon i-SENSYS MF5840dn

Horizontal white lines

Horizontal white line appears in image

Cause	Solution
1) Horizontal scratches on the photosensitive drum	Replace the cartridge.
2) The fixing film is defective	Replace the fixing unit.
3) Scratches/stain on the Developing Sleeve	Replace the cartridge.

Loose toner

Toner image is not fully fixed on the media

Cause	Solution
1) The pressure roller is not within nip-width specifications	See "MAINTENANCE AND SERVICE" to check the nip-width specifications. If the pressure roller is not within the specifications, replace the fixing unit.
2) The pressure roller is dirty	Replace the fixing unit.
3) The pressure roller is scarred or dent	Replace the fixing unit.
4) Scratches or foreign substance on the fixing film	Replace the fixing unit.
5) The thermistor has deteriorated	Replace the fixing unit.

Misformed image

Image is misformed

Cause	Solution
1) Poor contact exists to the connectors on the laser scanner unit	Reconnect the connectors: J801 and J802
2) Poor contact exists to the connectors on the formatter	Reconnect the connectors: J3 and J7
3) The laser scanner unit is defective	Replace the laser scanner unit.
4) The high-voltage power supply is defective	Replace the engine controller unit.